This invention relates to the improvement in the sawing of timber, and in particular to a portable saw mill frame facilitating the sawing of logs into lumber products at the location of the felled trees thereby eliminating the necessity to transport the harvested logs to a conventional saw mill for a processing.
Various problems have been encountered with prior portable mill frames. Portable mills are, in general, of a fixed length and are not adjustable to the exact length of the sawed timber, particularly if the timber is of an extraordinary length. They also lack sufficient support for cutting and log holding elements.
Canadian Patent 904,723 (Pluckhahn) discloses a portable sawmill including a longitudinal beam along which a transverse holder of a chain saw support is cantilevered, with the chain saw fixed at a free end of the transverse holder. The device must have insufficient stability. Canadian Patent 1,133,800 (Reece) shows a somewhat similar arrangement having the same drawback of a relatively low stability due to the mounting of the chain saw at a free end of a transverse holder. Canadian Patent 1,037,835 (Paquette) present a rigid rectangular frame with the saw holding device guided along top rails spaced a substantial distance above the ground. The device must either be placed over a log or a log must be inserted endwise into the frame. In any case, the improved rigidity of the frame (over the first two prior art references) is offset by inconvenience of operation.
It is an object of the invention to provide a portable saw mill which is easily transported to the actual sawing location and is easily assembled, operated and dismantled. Another object is to provide a portable saw mill, in which the log holding frame base and tracks for the saw carriage provide an improved stability for the sawing element, an unhindered and smooth movement of a saw carriage, and an easy log loading onto the frame base.
A still another object of the invention is to provide a portable saw mill in which the saw carriage is stabilized to eliminate vibration of the saw causing uneven cuts and producing unwanted and dangerous torque movements of the saw, of the log holding clamps and of the saw carriage.
A yet another object is to provide a portable saw mill frame in which a saw can be mounted on the carriage cross-beam for adjustment for selected thickness of a series of cuts so that logs are then sawed into exact sized lumber products of a high professional quality.
Another object of the invention is to provide a portable saw mill frame in which cutting length can be easily extended to the length required for sawing of an especially long log.
In general terms, the invention provides a portable sawmill frame comprising, in combination:
(a) a frame base having two opposed ends and two opposed sides; PA1 (b) said sides defining two opposed tracks, each track being generally coincident with a top portion of a side beam, each side beam comprising an underside adapted to be placed on the ground when the frame is in an assembled state; PA1 (c) a carriage including rollers adapted to roll on said tracks to allow a rolling movement of the carriage along the tracks; PA1 (d) two uprights fixedly secured to said carriage; PA1 (e) a cross-beam secured to the uprights near upper ends thereof and extending transversely of the carriage, whereby the cross-beam and the uprights define a rectangular structure having the general shape of an inverted "U"; PA1 (f) a chain saw holding device slidable along said cross-beam and including displacement device for selectively displacing the a respective chain saw to a desired location transversely of the carriage; and PA1 (g) said frame base including mounting device for fixedly securing log clamping devices to the frame.